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M-S stereo |
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In
the M-S stereo technique, one microphone with any pick-up pattern picks
up the sound from the front (middle) while another microphone with a
figure-of-eight pick-up pattern is positioned at right angles to it
(side). The M-S stereo technique produces an optimum mono signal, and
can be used to infinitely change the included angle. |
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Pick-up pattern |
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Also
known as polar pattern, directivity. According to their acoustic
design, microphones differ in their sensitivity towards sound from
different directions. Pressure microphones have a sensitivity that is
largely independent of direction (omni-directional pick-up pattern).
Pressure gradient microphones have the pick-up patterns wide cardioid,
cardioid, super-cardioid or figure-of-eight. Interference microphones
can be used to achieve a further concentration of the pick-up pattern
(lobar pick-up pattern). As a special case, dummy head microphones
achieve the pick-up pattern of the human ear/head (dummy head stereo). |
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Frequency response (microphone) |
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The
frequency response of a microphone is given within the limits defined
by the manufacturer. In studio condenser microphones it is generally
within the range of between 20 Hz and 20 kHz. |
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Maximum sound pressure level (passiv) |
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The
maximum sound pressure level is the maximum sound level which a
microphone can process electrically, which means that the THD of the
microphone amplifier is < 0.5%. The reference frequency is f = 1
kHz. If the microphone has an attenuator, this value can be increased
by 6-10 dB. |
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Output voltage |
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The (signal) voltage which a unit supplies at its output. |
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Equivalent noise level weighted as per CCIR 468-3 |
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The
output signal of every microphone always includes a low noise signal in
addition to the useful signal. In order to illustrate the extent of the
noise voltage, it is given as a fictitious sound pressure level. In an
ideally noise-free microphone, a sound pressure level of this magnitude
would result in an output voltage of the magnitude of the noise.
Self-noise is measured and weighted either in accordance with CCIR
468-3 or – in order to assimilate the measured result with the
listening impression of the human ear – in accordance with DIN/IEC 651
(so-called A-weighted). Studio condenser microphones generally have an
equivalent noise level of between 20 and 30 dB (CCIR) or between 10 and
20 dB(A). |
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Output impedance |
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Gives
the internal impedance of an a.c. source. If the input of a subsequent
load has the same input impedance, we speak of a matched impedance. The
maximum power is delivered to the load. |
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Impedance |
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Impedance
expresses the AC resistance of a microphone or a set of headphones. It
is dependent on frequency and is given at 1 kHz as the so-called
nominal impedance. Impedance is measured in ohms. In recent years, an
industrial standard has developed, setting the impedance of headphones
at 50 or 600 ohms. Sennheiser headphones are manufactured according to
this standard, thus practically ruling out connection problems. With
microphones, the input impedance of the following microphone amplifier
should have at least three times the value of the nominal impedance, in
order to prevent it from unnecessarily attenuating the microphone
signal. |
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Phantom powering |
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Almost
all studio microphones are supplied with 48V ±4V phantom power (P48,
IEC 268-15). This supply voltage is applied to both modulation lines,
while the return current flows via the cable screen. Some microphones
can also be powered by batteries or from plug-in mains adapters. |
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Connector |
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A standardised single or multi-pole plug for connecting units or accessories. |
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Dimensions |
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Weight |
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Operating temperature |
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Gives the range of temperatures at which a unit can be operated without damage. |
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